WASHINGTON, March 20 - With the election season heating up, the Bush administration and the Republican Party used a good deal of energy and charm on Monday to woo a group that has long been part of the Democrats' base: organized labor.

Homeland Security Secretary Michael Chertoff; Senator Chuck Hagel, Republican of Nebraska; and the Republican National Committee chairman, Ken Mehlman, spoke to the annual legislative conference of the main firefighters' union, saying they were eager to work with the union on issues of common ground.

The White House chief of staff, Andrew H. Card Jr., had been scheduled to speak, but canceled, citing illness. Mr. Mehlman praised the union for an increasing focus on bipartisanship and said if the firefighters and other unions worked with Republicans they could achieve more of what they were seeking, including greater preparedness for emergencies.

"We've sometimes disagreed, but we've always kept the dialogue open," he said. "There are areas where we can work together over the coming year."

Mr. Mehlman said the Republicans hoped to attract more union voters this year than in 2004, when 38 percent of union members backed President Bush, according to surveys of voters leaving the polls.

"I do think we can make greater inroads," he said.

Harold A. Schaitberger, the president of the International Association of Fire Fighters and the first prominent labor leader to back Senator John Kerry, Democrat of Massachusetts, for president in 2004, voiced the views of an increasing number of union leaders in saying it was important to work with Republicans.

"I realize that historically the Democrats have been friendlier toward workers," said Mr. Schaitberger, whose union has remained in the A.F.L.-C.I.O. as five unions have left the federation. "The bottom line is that at almost every level of government the government is split, and most legislatures are split. And you have to work both sides of the aisle to move an agenda."

The Teamsters, the service employees and other unions have begun cooperating with Republicans. But rarely have the Republicans made such strong overtures toward a union as they did on Monday toward the firefighters.

The firefighters have cachet because they are viewed as pillars in many communities and because 343 New York firefighters were killed on Sept. 11, 2001.

Sarah Chamberlain Resnick, executive director of the Main Street Republican Partnership, a group of Republican lawmakers that works closely with unions, said it was no coincidence that Republican leaders were courting union members.

"When the president is at 34, 36 percent in the polls, you have to begin to reach out," Ms. Resnick said. "The unions are not the president's base. So the White House is starting to reach out."

Her group has told unions that it is smart to reach out to Republicans.

"Republicans are in control, so it's good to have some friends who are in the majority," she said.

Mr. Chertoff promised that the administration would do a better job dispatching vital supplies to firefighters and other emergency workers when they respond to disasters.

Mr. Hagel urged the firefighters to help build a bipartisan consensus to deal with overarching problems like terrorism, poverty and health care.

Underlining the Republicans' difficulties in wooing union members, Howard Dean, the Democratic chairman, received far more applause than any Republican speaker. "We want American jobs that will stay in America," Mr. Dean said to thunderous applause.

He also called for "retirement security," saying Democrats, unlike many Republicans, would not seek to reduce public-employee pensions.

Some union leaders have voiced fears that labor's flirtation with bipartisanship could undercut efforts to return control of Congress to the Democrats, who have been friendlier to labor on issues like workplace regulation and raising the minimum wage.

As part of the bipartisan approach, Mr. Schaitberger said his union would back candidates, Republicans and Democrats, who have stood with the firefighters on issues like increased spending to hire first responders.

He said his union would back the re-elections of Republicans like Gov. Rick Perry of Texas and Senator Mike DeWine of Ohio but would seek to defeat Gov. Arnold Schwarzenegger in California and Senator Rick Santorum in Pennsylvania, two other Republicans.

"For those politicians who support our agenda, we will support them," Mr. Schaitberger said. "And for those who are looking to roll back the rights and improvements we've earned, we'll oppose them at every turn."

He criticized Mr. Bush for proposing to eliminate federal financing to hire additional first responders.

Mr. Schaitberger has revamped his union's political contribution so that 35 percent went to Republicans in 2004, up from 9 percent in 2000.

"We have one party that doesn't really care for us as labor and another that takes us for granted," he said. "I'm not sure which is worse."